title: Biochemical characterization of human epidermal retinol dehydrogenase 2.
abstract: The mRNA encoding a putative human enzyme named Epidermal Retinol Dehydrogenase 2 (RDH-E2) was found to be significantly elevated in psoriatic skin [Y. Matsuzaka, K. Okamoto, H. Tsuji, T. Mabuchi, A. Ozawa, G. Tamiya, H. Inoko, Identification of the hRDH-E2 gene, a novel member of the SDR family, and its increased expression in psoriatic lesion, Biochem. Biophys. Res. Commun. 297 (2002) 1171-1180]. This finding led the authors to propose that RDH-E2 may be involved in the pathogenesis of psoriasis through its potential role in retinoic acid biosynthesis and stimulation of keratinocyte proliferation. However, enzymatic activity for RDH-E2 has never been demonstrated. RDH-E2 is a member of the short-chain dehydrogenase/reductase (SDR) superfamily of proteins, and is most closely related to the group of SDRs comprised of both NAD(+)- and NADP(+)-dependent enzymes with activities toward retinoid and steroid substrates. In this study, we began the characterization of RDH-E2 protein in order to determine whether it might play a role in retinoic acid biosynthesis. The results of this study show that, similarly to other SDR-type retinol dehydrogenases, RDH-E2 appears to be associated with the membranes of endoplasmic reticulum. Furthermore, RDH-E2 expressed in Sf9 insect cells as a fusion to the C-terminal His(6)-tag and purified using Ni(2+)-affinity chromatography recognizes all-trans-retinol and all-trans-retinaldehyde as substrates and exhibits a strong preference for NAD(+)/NADH as cofactors. Specific activity of RDH-E2 toward all-trans-retinoids is much lower than that of other retinoid-active SDRs, such as human RoDH4 or RDH10. The preference for NAD(+) suggests that RDH-E2 is likely to function in the oxidative direction in vivo, further supporting its potential role in the oxidation of retinol to retinaldehyde for retinoic acid biosynthesis in human keratinocytes.
authors.affiliation: Department of Biochemistry and Molecular Genetics, Schools of Medicine and Dentistry, University of Alabama at Birmingham, 440B Kaul Genetics Building, Birmingham, AL 35294, USA.
authors.forename: Seung-Ah
authors.initials: SA
authors.lastname: Lee
authors.forename: Olga V
authors.initials: OV
authors.lastname: Belyaeva
authors.forename: Natalia Y
authors.initials: NY
authors.lastname: Kedishvili
mesh_terms: D000429:Alcohol Oxidoreductases / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D017931:DNA Primers; D004817:Epidermis / Q000201:enzymology*; D005455:Fluorescent Antibody Technique; D006801:Humans; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D018411:Spodoptera
chemical_list: D017931:DNA Primers; D011994:Recombinant Proteins; D000429:Alcohol Oxidoreductases; C022520:retinol dehydrogenase